What is the Ravs opinion regarding Biracha on desserts (after eating bread)?
Generally, food that comes as dessert and aren’t part of the meal require a bracha even though you washed for bread.
So if you eat an apple or cake as dessert you would be required to make a bracha.
Is there a specific food that you are having a question about?
eg Cake, Apple pie, Ice cream and ices.
All require a bracha
Should you bench birkat hamazon and then eat dessert?
No, first eat dessert and then say birkat hamazon. Birkat hamazon will cover the meal and the dessert.